New Jersey Gov. Chris Christie enters the Borough Hall in Fort Lee to apologize to Mayor Mark Sokolich on Thursday.

Two thirds of New Jersey residents polled believe the Fort Lee lane closures ordered in September by some members of the Christie administration were done for political retribution, and a third think the governor was personally involved in the decision, according to a poll released Monday.

Some 83% of residents are paying attention to the scandal at the George Washington Bridge, where a local lane closures caused traffic in Fort Lee for four days in September, according to the Monmouth University/Asbury Park Press Poll, the first conducted since documents revealed the administration’s involvement.

The poll showed that 13% believe that the lanes were closed in the course of a legitimate traffic study, the administration’s initial explanation for the closures.

More than two-thirds of residents polled believed the motive was political retaliation, the poll said, and 80% said they think more members of the Christie administration will be implicated. Several Christie allies have resigned or been dismissed from their posts.

Three quarters of those surveyed, however, said they saw the behavior as “pretty common” in politics and not unique to the Christie administration.

Residents still give Mr. Christie’s job performance high marks, though his support has dipped. Mr. Christie’s job-approval rating fell to 59% from 65% a month ago, the first time his popularity at home has taken a real hit since superstorm Sandy struck in fall 2012.

Among New Jersey Republicans, 89% approve of Mr. Christie’s job performance, up from 85% last month. Support among residents who identify as political independents dropped to 73% from 62% in December. Support among Democrats declined to 38% from 47%.

But personally? His support has cratered from a year ago. About 44% of New Jerseyans have a positive impression of Mr. Christie, down from 70% in February 2013.

“There has been a shift from largely positive opinion of the man to a situation where some New Jerseyans are not quite sure what to think of him,” said Patrick Murray, director of the Monmouth University Polling Institute.

Nationally, more people paid attention to the cold weather, the U.S. economy and the unemployment debate in Washington, D.C., than the Christie bridge story, according to a Pew Research Center poll. Six in 10 people said their opinion of the Republican governor hasn’t changed, while 16% said they had a less favorable view of him and 6% said they had a more favorable view.

For months, Mr. Christie said he wasn’t aware of any political motivations to the lane closures and assured reporters that his staff was not involved and knew nothing.

The Wall Street Journal reported in December that Christie’s top executive appointee at the Port Authority, Bill Baroni, had ordered the agency to close ranks and not publicly discuss the issue. “There can be no public discourse,” Mr. Baroni wrote in e-mails published by the Journal.

The poll surveyed 541 people between, and the sample has a margin of error of about 4%.